<html>

<head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <title>无标题文档</title>
    <style type="text/css">
        body {
            font-family: Verdana;
            font-size: 14px;
            margin: 0;
            background: #E9E9E9;
        }

        .clearfloat {
            clear: both;
            height: 0;
            font-size: 1px;
            line-height: 0px;
        }

        #container {
            margin: 0 auto;
            width: 900px;
            background: #FFFFFF;
            padding: 15px;
        }

        #header {
            height: 100px;
            background: #6cf;
            margin-bottom: 5px;
        }

        #menu {
            height: 30px;
            background: #09c;
            margin-bottom: 5px;
            line-height: 30px
        }

        /* #mainContent {} */

        #sidebar {
            float: right;
            width: 180px;
            height: 90px;
            line-height: 90px;
            background: #9ff;
            margin-bottom: 5px;
            padding-left: 20px;
        }

        #content {
            float: left;
            width: 670px;
            height: 160px;
            background: #cff;
            margin-bottom: 5px;
            padding: 40px 0 0 25px;
        }

        #footer {
            height: 60px;
            background: #6cf;
        }
    </style>
</head>

<div id="container">
    <div id="header">这是头部</div>
    <div class="clearfloat"></div>
    <div id="menu">这是导航</div>
    <div class="clearfloat"></div>
    <div id="mainContent">
        <div id="sidebar">这是侧边栏</div>
        <div id="content">2列右窄左宽、高度自适应+头部+导航+尾部</div>
    </div>
    <div class="clearfloat"></div>
    <div id="footer">这是尾部</div>
</div>

</html>